Great Britain 1840 1d Deep blue 'Rainbow trial' State 3(a), SG DP20.
Superb unused bottom left hand corner marginal example with manuscript endorsement to margin 'F' ½ Pruss' by Edwin Hill.
These were produced to test various combinations of stamp and cancellation ink. The voided corners of State 3 are more uniform in shape compared with the ragged corners of States 1 and 2.
Most attractive and scarce.
Accompanied with a 1996 Royal Philatelic Society (RPS) Certificate of Authenticity.